Such a small piece of Silicon, so strategic PHY IP

By SemiWiki

May 2, 2012

How could I talk about the various Interface protocols (PCIe, USB, MIPI, DDRn…) from an IP perspective and miss the PHY IP! Especially these days, where the PHY IP market has been seriously shaken, as we will see in this post, and will probably continue to be shaken… but we will have to wait and look at the M&A news during the next few weeks or so.

Before looking at these business related movements, doing some quick evangelization about what exactly is a PHY. The acronym comes from “PHYsical Media Attachment” (PMA) which described the part of the function dealing with the “medium” (PCB or optical). As of today, the vast majority of the protocols define high speed differential serial signaling where the clock is “embedded” in the data, at the noticeable exception of DDRn protocol where the clock is sent in parallel with the (non differential and parallel) data signals. The first reaction when seeing the layout view of an IC including a PHY function is that it’s damn small! A nice picture is always more efficient that a long talk, so I suggest you to look at the figure below (please note that the chip itself is a mid size IC, in the 30-40 sq. mm range).

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